Various means have been used in the prior art to prevent explosive materials from entering the internally threaded nose end of a shell casing. The prior art used a molded neoprene flanged tubular member having an externally threaded outside diameter and a smooth inside diameter. The externally threaded portion of the prior art device was manually pushed into the threaded open orifice of the shell casing. The inner bore of the thread protector had a diameter which provided a slight interference fit with a funnel inserted therein so that a seal could be effected between the funnel and the shell. The problem with above mentioned prior art was that the sealing action was not positive because of the frequent variation in diameter tolerances between the molded thread protector and the loading funnel. Experience has shown that it is very difficult to consistently maintain proper tolerences on a molded neoprene member and in addition very difficult to use an automated shell filling operation therewith because the flexibility of the neoprene thread protector made it difficult to pick up and easily insert.